Developed by General Electric
in the early 1960s, the "Vulcan" series of miniguns is available in many
calibers from 5.56 mm (0.223 in) up to 25 mm (1.0 in). The 0.30 caliber
(7.62 mm) GAU-2 version was first deployed by the Air Force for use on
light aircraft and helicopters, but has since been adopted by the Army,
Marines and Navy for the same purposes. These guns are widely used,
with the U.S. Army alone purchasing over 9,500 M134 guns. In the
last few years, the Navy has started using these weapons on ships to supplement
the 25 mm Chain Gun and venerable 0.50
in "Ma Deuce" M2 BMG.

The term "Vulcan" was originally the
GE Project Name for the first Gatling-type electric-powered minigun and
is now a slang term for all of these electric Gatling guns.

The GAU-17/A gun system consist of a
six-barrel rotary gun, a gun control assembly with electrical cables, gun
drive motor unit, a delinking feeder, flexible ammunition feed chutes and
an ammunition storage system. Gun component parts, such as the rotor,
housing, feeder/delinker, and barrel clamp/flash suppressor, are available
in either steel or lightweight titanium.

Quoting from a USMC HMLA OAG Action
Item: "The GAU-17 minigun, while providing [an] outstanding volume
of fire, is notorious for jamming." Most of the problems occur in
the Feeder/Delinker assembly. One manufacturer of this weapon, Dillon
Aero, Inc., claims its Feeder/Delinker is much more reliable with an average
of 30,000 rounds between stoppages.

This weapon is also used on surface
warships in the British Royal Navy.

2) M134D is the minigun itself. Other
designations are usually for the "gun assemblies" that include the mounting.
The GAUSE designation appears only on text released with U.S. Navy photographs.
It may represent a "sailor-alt" rather than an official U.S. Navy designation,
although I have been unable to confirm that one way or the other.
I have been told by USN personnel that the "SE" in GAUSE probably stands
for "Shipboard Equipment" and refers to the entire gun and mounting assembly
rather than to just the minigun itself.

3) The original design of the 1960s had
a fixed rate of about 6,000 rounds per minute. This was unsustainable
over any period of time and the weapon was redesigned to add a transmission
housing at the motor, giving the weapon a variable speed of 2,000 or 4,000
rounds per minute. On the newer Dillon Aero Inc. version, the rate
of fire is determined by the gun drive unit used, with drive units giving
either 3,000 or 4,000 rounds per minute available. There is no speed
selection on this version other than by assembling a different gun drive
motor to the the gun system assembly. The 3,000 ROF drive motor takes
0.5 seconds to spin up to speed and 0.25 seconds to spin down to stop.
When the trigger is released, there is a delay until all six barrels have
been cleared by fire. This ensures that no live ammunition is left
in the firing chambers, thus eliminating cook-off problems.

.

Ammunition

.

Type

Fixed

Weight of Complete Round

Ball - N/A

Projectile Types and Weights

Ball - 0.34 oz (9.65 gm)

Bursting Charge

None

Projectile Length

N/AComplete Round - 2.75 in (6.99 cm)

Propellant Charge

N/A

Cartridge

7.62 x 51 mm

Muzzle Velocity

2,800 fps (854 mps)

Working Pressure

N/A

Approximate Barrel Life

100,000 rounds per barrel cluster

Ammunition stowage per gun

Up to 4,400 rounds of ready ammunition

Notes:

1) These guns use standard NATO 7.62 mm
percussion primed ammunition which is usually supplied in in 1,000 round
disintegrating-link belts.